1. Field of the Invention
The invention relates to a plate-link chain, especially for use in a continuously variable, conical disk transmission, such as a CVT transmission. The individual link elements of the chain are formed by link sets constituted by connected chain links, preferably as pairs, which include rocker members inserted into openings in the plate links and having rocker faces supported against each other. The invention also relates to a method for producing that type of chain.
2. Description of the Related Art
Plate-link chains of that type are known in the art. Examples are disclosed in German Patent Publication DE 197 08 865 and in the publications cited therein, EP 0 518478, and EP 0 741 255.
In order to increase the load bearing capacity of plate-link chains of the designated kind, following assembly of the plate links and the rocker members into a straight, open length of chain, the elongated plate-link chain is subjected to a stretching process by applying to it a substantial tensile force. In that manner, contact areas of the plate links, between the plate links and the rocker members, of all the plate links in a row are equally plastically deformed. Stretching a straight chain results in an equal plastic deformation of the plate links in the contact surface areas, so that the plate links of a row of plate links are equally lengthened or have the same inner width. That has the disadvantage that if the plate-link chain is loaded during operation of the continuously variable transmission, the life span and performance of the chains are not optimized.
A purpose of the invention is to provide a plate-link chain, and a method for producing a plate-link chain that can withstand a higher load than state-of-the-art plate-link chains, or that has a longer life span at the same operating load.
According to the invention, that objective is achieved in the above-mentioned plate-link chains by stretching the plate-link chain when in the closed condition.
The objective according to the invention is also achieved in that, with regard to a plate-link chain as mentioned above, the plate links have varying inner widths that vary as a function of the width of the chain. In accordance with the invention, that can be achieved by stretching the plate-link chain while it is in a loop in a closed condition.
The notion of plate inner width corresponds with the distance between the contours at which the two outer rocker members contact the plate link. Therefore, that is a distance that is independent of whether the plate link has one central opening or two openings for receiving the rocker members. That is further presented in the drawing figure descriptions.
In another exemplary embodiment, however, it is advantageous if the plate links are manufactured with different plate link inner widths, by a manufacturing process such as a stamping process or a cutting process, for example by means of a laser or the like, and the individual plate links are then stretched equally or differently and assembled with each another, or the assembled chain is stretched while in a loop.
Additionally, in a further exemplary embodiment, it is appropriate for the plate links with the same plate link inner widths to be produced by a stamping process, and to be varyingly stretched and assembled with one another. In this exemplary embodiment the stretching process can also be performed on the individual plate links before assembly, or on the assembled chain when it is in a loop.
According to another object of the invention, the inventive solution can also be achieved with regard to an above-identified plate-link chain if the plate links have different degrees of stretch, as a function of the width of the chain.
That can advantageously be achieved in that the plate links having equal or different plate link inner widths are stretched at different degrees and assembled with each another. That can also be achieved by stretching when the chain is in a loop
In accordance with another inventive concept, the purpose can also be achieved in a plate-link chain as discussed above in which the plate links, as a function of the width of the chain, have a different angle between the contact areas and an axis that is transverse to the longitudinal direction of the chain. A modulation or variation of the angle is thereby achieved across the width of the chain that allows a relatively good fit or arrangement of the plate links to the rocker members that become partially bent during the operation of the chain.
In accordance with another inventive concept, the purpose can also be achieved in a plate-link chain as discussed above if a stretching load is applied to the plate links during the stretching process at an angle that varies relative to the longitudinal direction of the plate links. The plate links will thereby be stretched at different positions of their contact areas with the rocker members, and in that way the plate links will be strengthened so that when loaded during the operation of the chain they will exhibit sufficient strength both as a straight length between pairs of conical disks as well as in the area of the pairs of conical disks.
It is especially advantageous if the plate links are stretched individually and subsequently assembled with one another. In another exemplary embodiment it is useful if the plate links are stretched when in an assembled state as a closed chain, in particular in a loop arranged between two conical disk pairs of a device.
The invention advantageously relates to plate-link chains in which at least one of the end faces of the rocker members per link, associated with a respective conical disk, transfers the frictional forces between the conical disks and the plate-link chain. Thus, depending on the specific application of the exemplary embodiment, it can be useful for the rocker members either to be equally long or to have different lengths.
But the invention also advantageously relates to plate-link chains that, in addition to the rocker members, have cross pins that transfer the frictional forces between the conical disks and the plate-link chain.
It is especially advantageous if adjacent plate links that are positioned along the edge of the plate-link chain are elongated considerably more than the plate links that are in the center of the plate-link chain, or if adjacent plate links that are positioned along the edge of the plate-link chain have a larger plate-link inner width than the plate links that are in the center of the plate-link chain.
Furthermore, it is useful if during a stretching process areas of the plate links that contact the rocker members are plastically deformed, so that an angle is formed between the contact areas and a direction that extends transversely to the longitudinal direction of the chain.
It is useful if during a stretching process the plastic deformation of the contact areas of the plate links that are positioned along the edge of the plate-link chain is greater than that of the plate links that are positioned in the center of the plate-link chain. It is also useful if the plastic deformation of the contact areas of the plate links, viewed over the entire width of the chain, has a curved shape or the shape of a polynomial of the nth degree.
It is especially advantageous if during the stretching process the plate-link chain is received within the gaps between two pairs of conical disks and rotational speed and/or torque is applied to it.
It is also useful for the stress on the plate-link chain during the stretching process to be provided by an axial load by pressing together the conical disks and/or by pulling apart the shafts of the pairs of conical disks. Correspondingly, the invention also relates to a device for stretching a plate-link chain. It is useful in that context if the conical disks of the pairs of conical disks are movable relative to one another or are fixed.
When stretching the plate-link chain, it is useful if the torque that can be applied during the stretching process is considerably greater than the nominal torque during the operation of a transmission that is provided with the plate-link chain.
It is also useful if the torque that can be applied during the stretching process is between zero and ten times, preferably three to five times, the nominal torque during normal operation of a transmission that is provided with a plate-link chain.
It is also useful if the tension in the strand of the chain during the stretching process is greater than the nominal tension during normal operation of a transmission that is provided with a plate-link chain.
The present invention also relates to a method for producing a plate-link chain, especially in accordance with one of the above-identified techniques. Additionally, the present invention relates to a method for stretching a plate-link chain.